Traditional research and development method of new materials can be concluded to a “trial and error method”. In the trial and error method, firstly, based on the existing theories or experiences, the matching ratio of components of the target material is predicted or selected, and then the target material is subjected to such preparation and processing as melting, smelting and heat treatment etc. in small batches (ordinarily, dozens of kilograms of metal materials are required), and then the components are adjusted and optimized according to the characterization results of the prepared samples, preparation and characterization are conducted once again, and the materials satisfying requirements are finally obtained after repeated cycles. However, such a discrete sample preparation, trial and error method, in which only one sample is prepared in one experiment is low in efficiency and high in R&D cost. It is a worldwide statistic that it would spend about 5-12 years in average on R&D of a new material because of the low efficiency and high cost of R&D, which become a bottleneck of the development of modern new materials. (Introduction to Material Genome Initiative, Nature, 2014, 36 (2): 89-104).
The current material preparation method (especially the preparation technology of block materials) is generally used for a certain material system. It is low efficient and high costs because only one component ratio of sample could be prepared each time, which causes the following five major technical defects:
1. The component of the prepared material is single. The component of a material plays a leading role in the performance of the material. With the smelting preparation method of the metal material as an example, in the existing method, only one component combining mode can be selected once for blending and smelting, thereby greatly reducing the efficiency of determining the matching conditions of optimal component combination.
2. The efficiency of external heating during the preparation of materials is low. In traditional heating method, by utilizing external heat source, conductive heating is gradually performed from the outside to the inside via heat radiation, and the ambient temperature can only be raised to a set degree after a long time, moreover, the efficiency of temperature rise and heating homogenization of materials will also be influenced by size of material volume and such parameters as heat conductivity etc., therefore, the radiation heating manner is long in heating time and low in heating efficiency.
3. The controlling temperature during material preparation is unique. The control of temperature conditions is a key factor in the preparation of materials. If the temperature is too low, various components cannot be melted completely, then the components will produce nonuniform, agglomerated, mingled and defected phenomena etc.; if the temperature is too high, then it will result in that impurities are difficult to be removed and the energy consumption is increased. In the existing method, only one temperature can be selected during each preparation, that greatly reduces the efficiency of selecting the optimal preparation temperature conditions.
4. The controlling temperature of heat treatment of materials is single. The microstructure of materials plays a decisive role in material performance, materials with the same components can be converted into different microstructures and thus have different performances through heat treatment process under different temperatures. The existing method cannot realize heat treatment of a single material under various temperatures at the same time, which means that more microstructures cannot be obtained, leading to the difficulty in screening out the microstructure combination which has the greatest effect in improving the performance of materials, thereby greatly reducing the efficiency of exploring the process conditions of heat treatment.
5. The consumption of raw materials for preparing single sample is large, which leads to higher cost. In the R&D stage, the consumption of single sample is also very large in a certain degree when new materials are in trial production in small batches, for example, the weight of single metal materials in the trial production is often dozens of kilograms, and the repeated experiments are needed, which are also the main reasons of high R&D cost.
Microwave belongs to electromagnetic wave, and when it is interacted with objects, it can accelerate the movement of the microscopic particles in the object, and convert the electromagnetic energy of the microwave into heat energy, thereby realizing the heating of objects. Different from the heating of external radiation, microwave can heat both the outside and the inside of the samples at the same time. Microwave heating not only has the advantages of material selection characteristic, high temperature rise speed and high heating efficiency etc, but also can lower the reaction temperature, shorten the reaction time, promote energy saving and reduce material consumption; meanwhile, since microwave heating does not generate any gas, it is also a green and efficient heating method (Peng Jinhui, Yang Xianwan: New Application of Microwave Energy [M]. Kunming: Yunnan Science and Technology Press, 1997: 75-78.).
High throughput synthesis is an important part of Material Genome Initiative, and its task is to manufacture material microchips with hundreds of combinations in one time in a short time. Then different high throughput characterization methods are adopted to rapidly screen out the combination modes satisfying target requirements, and its core concept is to change the sequential iterative method adopted in traditional material research into parallel processing, and lead to a qualitative change of material research efficiency with quantitative changes (Wang Haizhou, Wang Hong, Ding Hong, Xiang Xiaodong, Xiang Yong, Zhang Xiaokun: Progress in high-throughput materials synthesis and characterization[J]. Science and Technology Review, 2015, 33 (10): 31-49). However, there's still no report on the adoption of microwave heating to obtain a controllable temperature gradient field and a high throughput synthesis method of materials.